Simplify script/bootstrap.

We shouldn't need to delete `Brewfile.lock.json` because it doesn't actually lock anything; it just records versions that were installed.

If we don't delete it, new `brew bundle install` run just adds info about what was installed during its run to the existing info about previous bundle installs.

By not deleting, the code can be simplified as per this commit.

Partial #638

Signed-off-by: Ross Goldberg <484615+rgoldberg@users.noreply.github.com>

script/bootstrap

@@ -19,13 +19,11 @@ function usage {
   exit 1
 }
 
-frozen=''
-
 # Detect presence of `-f` frozen option
 while getopts "f" opt; do
   case "${opt}" in
     f)
-      frozen='-f'
+      frozen='--no-lock --no-upgrade'
       ;;
     *)
       usage 1>&2
@@ -35,15 +33,8 @@ done
 
 printf $'==> 👢 Bootstrapping (%s)\n' "$(script/version)"
 
-# Install Homebrew tools
-if [[ "${frozen}" == "-f" ]]; then
-  # --no-lock Don't touch Brewfile.lock.json
-  brew bundle install --no-lock --no-upgrade --verbose
-else
-  # Allow upgrades
-  rm -f Brewfile.lock.json
-  brew bundle install --verbose
-fi
+# shellcheck disable=SC2086
+brew bundle install ${frozen} --verbose
 
 mise settings set experimental true
 mise install --verbose